Parameter Space for Chemical Vapor Deposition Graphene in Cold-Wall Reactors under High Precursor Flow Rate

Cold-wall chemical vapor deposition growthof crystallinegraphene depends on the catalyst pretreatment, pressure, temperature,gas flow rates, etc. A scanning electron microscopy image-processingmethod gathers information from partially grown crystals and enablesa quantitative analysis of the growth quality (polycrystallinity andradial growth rate). Cross-analysis with a gas-phase equilibrium thermodynamicmodel broadens the understanding of the system and improves the selectionof the growth parameters. Nowadays, promising proof-of-concept graphene technologiesalreadyexist, although converting them into a commercial success requiresa high-throughput fabrication process providing a high-quality material.Chemical vapor deposition (CVD) has proven to be the enabling technologyfor this purpose. However, as typical CVD systems are based on laboratory-scaletubular hot-wall reactors, a comprehensive study is required to translatethe optimal thermodynamic configuration into industry-ready CVD cold-wallreactors, capable of increasing the growth area and the process efficiencyand yield, hence drastically reducing the costs. In this work, a studyon how the thermodynamic parameters affect the growth dynamics andthe material quality in a cold-wall reactor under high precursor flowrate is presented. The growth dynamics have been assessed in termsof the lateral growth rate and the nucleation density by means ofscanning electron microscopy and image-classification techniques,whereas the quality of the single crystals has been evaluated throughRaman mapping and electrical measurements. The parameter space definedby the experimental data has been compared with the predictions basedon free Gibbs energy minimization, obtaining an overall good qualitativeagreement and proving the suitability of the high precursor flow rateregime for achieving a high-quality material at moderate growth times.